1. Field of the Invention
The present invention relates to droplet ejection using a liquid jet recording head with thermal elements, and more particularly, to a liquid droplet forming method employing a two-part drive signal and time-division driving.
2. Description of the Prior Art
In the related field there are already known ink jet recording apparatus for example of drop-on-demand type, which are recently attracting attention because of their negligibly low noise and absence of an unnecessary ink deposit when recording. Such recording is considered particularly useful in the ability of recording on plain paper without a particular fixing treatment. In the field of such drop-on-demand type ink jet recording, there have been proposed various apparatus some of which are already in commercial use, while others are still in the course of development.
In summary, the ink jet recording of the drop-on-demand type performs recording by emitting a droplet of recording liquid, called ink, from a small orifice in response to an instruction signal, and depositing the droplet onto a recording material. In the known methods, the droplet generation is achieved for example by the use of a piezoelectric element.
The present invention relates to a novel drop-on-demand type ink jet recording method which is different from the conventional method utilizing the piezoelectric element and which effects the droplet emission from a small orifice by applying a drive signal to the liquid introduced to a small liquid chamber, thereby causing bubble formation in the liquid. Also in a related field U.S. Pat. No. 3,878,519 discloses another apparatus, which while not requiring pressurizing and deflecting means, does provide droplets of insufficient evenness because of a weak droplet forming force and further requires a liquid recovery mechanism for unused droplets, and thus cannot be compactized.